JP5777368B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to detection of a remaining amount of toner that is a developer in an electrophotographic image forming apparatus such as a laser printer, a copying machine, and a facsimile.

  In the conventional image forming apparatus, there is an example in which the remaining amount of toner in the toner container is detected by a capacitance detection device. For example, in the toner remaining amount detecting device described in Patent Document 1, a flexible member having a detection target at the tip is connected to a stirring member and rotates following, and enters and rotates in the toner. At this time, when the connecting portion of the flexible member and the stirring member enters the toner, the entire flexible member is deformed flexibly and continuously enters the toner at the same location, and the same track in the toner. Draw and rotate. Therefore, the detection target at the tip of the flexible member also rotates and moves along the same track as the flexible member. Further, when the toner is reduced to a level below a certain level and the connecting portion with the stirring member does not enter the toner, the vicinity of the tip of the flexible member slides on the toner surface, and the detection target also slides on the toner surface. Move. Here, when the toner is reduced to below a certain level and the height of the toner surface is gradually lowered, the position of the detected object that slides and moves on the toner surface is also gradually lowered. That is, when the toner is reduced below a certain level, the position of the detection object that moves on the surface of the toner is also lowered according to the remaining amount of toner.

  On the other hand, the electrostatic capacity sensor detects the electrostatic capacity between the object to be detected moving on the toner surface, and the electrostatic capacity changes according to the distance between the two. Since the electrostatic capacity sensor is arranged at the lower part of the toner container, when the toner is reduced to a level below a certain level and the position of the detection object moving on the toner surface is lowered, the electrostatic capacity sensor and the The distance between the detection bodies is shortened, and the capacitance between them is increased. That is, the capacitance between the capacitance sensor and the detection object changes according to the remaining amount of toner.

Japanese Patent No. 4137703

  However, the above toner remaining amount detection device has the following problems. When the toner is filled at a certain level or more, the connecting portion between the agitating member and the flexible member enters the toner, so that the trajectory drawn by the flexible member and the detection object hardly changes. That is, when the toner is more than a certain level, the detected capacitance hardly changes. Therefore, if the toner is above a certain level, the remaining amount of toner cannot be detected successively and accurately.

  The present invention has been made in such a situation, so that the remaining amount of toner can be detected sequentially until the toner becomes full from the full state, and the remaining amount of toner can be accurately measured even when the stirring member is operating at high speed. The purpose is to detect well.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) rotates around a rotational axis in a detachable developing unit for accommodating a developer, a rotary member that having a flexible deflected by the resistance of the developer, the rotation shaft side of the rotary member a first conductive of the detected member disposed, and a second conductive of the detected member disposed on the distal end side of said rotary member, disposed outside the vicinity of the wall surface of the developing unit A detection electrode; a first capacitance between the first conductive member to be detected and the detection electrode ; and a second static electricity between the second conductive member to be detected and the detection electrode. And a conversion unit that detects the combined capacitance and converts the capacitance into an electric signal, and a measurement unit that measures a time width in which the electric signal converted by the conversion unit exceeds a predetermined threshold. And a judging means for judging the amount of the developer based on the time width measured by the measuring means. Image forming apparatus characterized by.

(2) rotates around a rotational axis in a detachable developing unit for accommodating a developer, a rotary member that having a flexible deflected by the resistance of the developer, the rotation shaft side of the rotary member a first conductive of the detected member disposed, and a second conductive of the detected member disposed on the distal end side of said rotary member, disposed outside the vicinity of the wall surface of the developing unit A detection electrode; a first capacitance between the first conductive member to be detected and the detection electrode ; and a second static electricity between the second conductive member to be detected and the detection electrode. A conversion unit that detects a combined capacitance of the capacitance and converts the capacitance into an electrical signal; a measurement unit that measures a detection level of the electrical signal converted by the conversion unit; and the measurement unit Determination means for determining the amount of the developer based on the detection level measured in step (b). An image forming apparatus.

(3) A rotating member installed on the rotating shaft that rotates around a rotating shaft in a detachable developing unit that houses the developer and is bent by the resistance of the developer; and the rotating member Capacitance of the conductive member to be detected, a detection electrode disposed in the vicinity of the outer wall surface of the bottom of the developing unit, and the detection member and the detection electrode is detected, and the electrostatic capacitance is detected. Conversion means for converting a capacity into an electric signal, first measurement means for measuring a time width in which the electric signal converted by the conversion means exceeds a predetermined threshold, and a detection level of the electric signal converted by the conversion means A second measuring unit that measures the amount of the developer based on a time width measured by the first measuring unit or a detection level measured by the second measuring unit; The determination means is measured by the first measurement means When it is determined that the amount of the developer is less than a predetermined amount based on the gap, the determination unit determines the amount of the developer based on the detection level measured by the second measurement unit. When it is determined that the amount of the developer is equal to or greater than a predetermined amount based on the time width measured by the first measuring unit, the determining unit is measured by the first measuring unit. Control means for controlling to determine the amount of the developer based on a time width;
An image forming apparatus comprising:

  According to the present invention, the remaining amount of toner can be sequentially detected until the toner becomes empty from the full state, and the remaining amount of toner can be accurately detected even when the stirring member is operating at high speed.

Sectional drawing which shows the structure of the image forming apparatus of Example 1 thru | or Example 3. Sectional view of the developing unit of Example 1 Circuit diagram of toner remaining amount detection according to the first exemplary embodiment. Characteristic graph, waveform, and table T of toner remaining amount detection in the first embodiment Flow chart of toner remaining amount detection according to the first exemplary embodiment. Characteristic graph of toner remaining amount detection of Example 2, table L Flowchart of toner remaining amount detection according to the second exemplary embodiment Sectional view of the developing unit of Example 3

  Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the configuration of the invention.

[Configuration of Image Forming Apparatus]
FIG. 1 is a configuration diagram of a “color laser printer” which is an image forming apparatus of this embodiment. The color laser printer shown in FIG. 1 (hereinafter referred to as “main body”) includes process cartridges 5Y, 5M, 5C, and 5K that are detachable from the main body 101. Although these four process cartridges 5Y, 5M, 5C, and 5K have the same structure, they are developers of different colors, that is, yellow (Y), magenta (M), cyan (C), and black (K) (hereinafter referred to as “developers”). The difference is that an image is formed by toner). Hereinafter, the symbols Y, M, C, and K may be omitted unless a specific color is described. The process cartridge 5 is composed of three components: a developing unit, an image forming unit, and a waste toner unit. The developing unit includes a developing roller 3, a toner supply roller 12, a toner container 23, and a stirring mylar 34. Further, the image forming unit includes a photosensitive drum 1 and a charging roller 2 which are image carriers. The waste toner unit has a cleaning blade 4 and a waste toner collection container 24. A laser unit 7 is disposed below the process cartridge 5 and performs exposure based on an image signal to the photosensitive drum 1. The photosensitive drum 1 is charged to a predetermined negative potential by the charging roller 2, and then an electrostatic latent image is formed by the laser unit 7. The electrostatic latent image is reversely developed with negative toner attached by the developing roller 3 to form Y, M, C, and K toner images, respectively. The intermediate transfer belt unit includes an intermediate transfer belt 8, a driving roller 9, and a secondary transfer counter roller 10. Further, a primary transfer roller 6 is disposed inside the intermediate transfer belt 8 so as to face each photosensitive drum 1, and a transfer bias is applied to the primary transfer roller 6 by a bias applying device (not shown).

  Each photosensitive drum 1 rotates in the arrow direction, and the intermediate transfer belt 8 rotates in the arrow A direction. Then, by applying a positive bias to the primary transfer roller 6, the toner images on the photosensitive drum 1 </ b> Y are sequentially primary transferred onto the intermediate transfer belt 8, and the secondary transfer roller in a state where the four color toner images overlap. 11 is conveyed. The feeding / conveying device includes a paper feed roller 14 that feeds the transfer material P from the paper feed cassette 13 that houses the transfer material P, and a transport roller pair 15 that transports the fed transfer material P. . Then, the transfer material P conveyed from the feeding / conveying device is conveyed to the secondary transfer roller 11 by the registration roller pair 16. In the transfer from the intermediate transfer belt 8 to the transfer material P, a positive bias is applied to the secondary transfer roller 11 to transfer the four color toner images on the intermediate transfer belt 8 onto the transfer material P transported. Next transferred. After transfer of the toner image, the transfer material P is conveyed to the fixing device 17 and heated and pressed by the fixing film 18 and the pressure roller 19 to fix the toner image on the surface. The fixed transfer material P is discharged by the paper discharge roller pair 20.

  On the other hand, the toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed by the cleaning blade 4, and the removed toner is collected in a waste toner collecting container 24. Further, the toner remaining on the intermediate transfer belt 8 after the secondary transfer to the transfer material P is removed by the transfer belt cleaning blade 21, and the removed toner is collected in a waste toner collecting container 22. A control board 80 in FIG. 1 is a board for controlling the main body, and is equipped with a one-chip microcomputer (hereinafter referred to as CPU) 40, and a storage unit such as a RAM and a ROM for storing table data and the like. ing. The CPU 40 collectively performs operations of the main body such as control of a drive source (not shown) related to the conveyance of the transfer material P, a drive source (not shown) of the process cartridge 5, control related to image formation, and control related to failure detection. Control. The video controller 42 controls the light emission of the laser in the laser unit 7 from the image data. The video controller 42 also interfaces with the user via a control panel (not shown). On this control panel, the remaining amount of toner for each color is displayed in a bar graph.

[Development unit configuration]
FIG. 2 is a cross-sectional view of the developing unit and the capacitance sensor substrate 331 constituting the process cartridge 5. FIG. 2A shows a state where the remaining amount of toner is about 50%, and FIG. 2B shows a state where the remaining amount of toner is about 10%. The toner 28 corresponding to each color of YMCK is stored in the developing unit and stirred by the stirring mylar 34. The stirring mylar 34 is installed on the rotary shaft 25 and rotates in the toner container 23 in the direction of the arrow around the rotary shaft 25. The rotation shaft 25 is provided with a detection mylar 351 that is a flexible rotation member for detecting the remaining amount of toner. The detection mylar 351 uses a general-purpose mylar film. The thickness of the stirring mylar 34 was 150 μm, and the thickness of the detection mylar 351 was 75 μm. Therefore, the detection mylar 351 has a larger amount of warping than the stirring mylar 34. The detection mylar 351 includes a conductive detected electrode 361 (detected member). Further, the capacitance sensor electrode 321 for detecting the capacitance functions as a toner remaining amount detection sensor. The capacitance sensor electrode 321 is disposed in the vicinity of the outer wall surface of the bottom portion of the toner container 23 when the process cartridge 5 is mounted on the main body 101. A capacitance sensor IC 33 is mounted on the capacitance sensor substrate 331, and a capacitance sensor electrode 321 and a reference electrode 320 are formed by a copper foil pattern. In addition, peripheral circuit components of the capacitance sensor IC 33 are mounted on the capacitance sensor substrate 331. The detected electrode 361 is for moving charges from the capacitance sensor electrode 321.

  As shown in FIG. 2A, when the detection mylar 351 rotates and the remaining amount of toner is large, the detection mylar 351 is deformed to the rear side in the rotation direction due to the resistance of the toner and greatly bent. When the remaining amount of toner is large in this way, the detection mylar 351 passes far from the capacitance sensor electrode 321, so that the capacitance is detected small, and the time width in which the detection level exceeds the threshold, that is, the detection time width is shortened. . On the other hand, when the remaining amount of toner is small as shown in FIG. 2B, the detection mylar 351 is small and bends and passes near the capacitance sensor electrode 321, so that the capacitance is detected to be large and the detection time width is long. Become. In this embodiment, the remaining amount of toner is detected using this principle. FIG. 2C is a perspective view showing the positional relationship between the detection mylar 351 and the detected electrode 361. The length of the detected electrode 361 in the radial direction is 30 mm. The lengths of the detection mylar 351 and the detected electrode 361 in the direction of the rotation axis 25 may be long enough to cover at least the detection surface of the capacitance sensor electrode 321. The lengths of the detection mylar 351 and the detection target electrode 361 in the radial direction need to be long enough to bend in contact with the bottom surface of the toner container 23 without the toner 28. The detection mylar 351 is a softer member than the stirring mylar 34, but is not limited to the material and thickness.

[Toner level detection circuit diagram]
FIG. 3 is a circuit diagram of toner remaining amount detection. The bypass capacitor 46 removes noise from the analog power supply terminal AVDD of the capacitance sensor IC33. Further, the bypass capacitor 47 removes noise from the digital power supply terminal DVDD of the capacitance sensor IC33. Each of the fixed resistors 43 to 45 divides a direct-current (DC) power supply voltage of 5.0 V and is connected to the THON input terminal and the THOFF input terminal of the capacitance sensor IC 33, and the THON input terminal is 1.4 V, The constant is set so that the THOFF input terminal is 0.8V. A reference electrode 320 is connected to the SREF terminal, and a capacitance sensor electrode 321 is connected to the SIN1 terminal. The reference electrode 320 is a copper foil pattern having the same area as the capacitance sensor electrode 321. The capacitance sensor IC 33 outputs level data, which is an electric signal obtained by converting the detected capacitance, from the PO1 output terminal and the SDN output terminal to the CPU 40 via the serial communication line.

[Characteristics of toner remaining amount detection]
Next, the toner remaining amount detection characteristic in this embodiment will be described with reference to FIG. FIG. 4A shows waveform data of the detection level and time (msec) of the capacitance sensor IC 33 when the remaining amount of toner is 10%. The CPU 40 (first measurement means) measures the time width at which the detection level of the capacitance sensor IC 33 is 60 or more and measures 12.5 msec. FIG. 4B is a characteristic graph of the remaining amount of toner (%) and the time width at which the detection level of the capacitance sensor IC 33 is 60 or more. When the remaining amount of toner is 0%, the time width when the detection level of the capacitance sensor IC33 is 60 or more is 13.7 msec. On the other hand, when the remaining amount of toner is 100%, the time width during which the detection level of the capacitance sensor IC33 is 60 or more is 8.0 msec. FIG. 4C is a table T showing the relationship between the time width (msec) at which the detection level of the capacitance sensor IC33 is 60 or more and the remaining amount of toner (%). Data of this table T is stored in the storage unit of the control board 80. The toner remaining amount between the table values is obtained by linear interpolation of the known toner remaining amount. Here, since the calculated detection level is a value in the present embodiment, the calculated detection level changes if the condition changes. The same applies to the numerical values in the table T for calculating the remaining amount of toner.

[Toner remaining amount detection flowchart]
Next, the flow of toner remaining amount detection will be described using the flowchart of FIG. Similarly, the flowcharts in the following embodiments are processed by the CPU 40. However, the present invention is not limited to this. For example, when an integrated circuit (ASIC) for a characteristic application is mounted on the image forming apparatus, it may have a function of any step. First, the CPU 40 rotates the stirring mylar 34 and the detection mylar 351 (S101). The CPU 40 serially communicates with the capacitance sensor IC 33 to set an initial value, and starts reading the detection level of the capacitance sensor IC 33 (S102). When the CPU 40 determines that it is not shorter than 0.5 seconds and not longer than 40 (Y in S103), the CPU 40 determines that the level is the initial state at the position where the detected electrode 361 is not present. Next, when the detection level of the capacitance sensor IC33 becomes 60 or more (S104, Y), the CPU 40 determines that the sensor signal rises and sets the timer to 0 (S105). The value 60 used for the determination in S104 is a so-called rising threshold value. Then, the CPU 40 starts a timer for measuring the time width (S106). Next, when the detection level of the capacitance sensor IC becomes 50 or less (S107, Y), the CPU 40 determines that the sensor signal falls (S108). The value of 50 used for the determination in S107 is a so-called falling threshold value. Then, the CPU 40 stops the timer (S108). The reason why the rising threshold of the detection level is set to 60 and the falling threshold is set to 50 is to provide hysteresis and prevent malfunction due to noise. Next, the CPU 40 reads the timer value (S109) and collates it with the table T (S110). Then, the CPU 40 notifies the video controller 42 of the remaining amount of toner corresponding to the collated value (S111), and the process ends.

Here, the period of the detection mylar 351 is about 1 second in this embodiment. If the CPU 40 determines that 2.0 seconds or more have passed in a state that is not 0.5 seconds or more and 40 or less (S103 N, S114 Y), the CPU 40 determines as follows. That is, it is determined that the capacitance sensor IC 33 is faulty, the detected electrode 361 is stopped at the detection position, or the communication abnormality between the CPU 40 and the capacitance sensor IC 33 (S115). In this case, the CPU 40 notifies the video controller 42 (S115), and the process ends. Note that the CPU 40 is 0. If it is determined that 2.0 seconds or more do not elapse for 5 seconds or more and 40 or less (S103 N, S114 N), the CPU 40 continues the process of S103. On the other hand, if the CPU 40 determines that 2.0 seconds or more have elapsed after becoming less than 60 in S104 (S104 N, S113 Y), the detected electrode 361 cannot be detected. The notification is sent to the controller 42 (S115), and the process ends. When the CPU 40 determines that 2.0 seconds or more have not elapsed after becoming less than 60 in S104 (S104 N, S113 N), the CPU 40 continues the process of S104. If the CPU 40 determines that 2.0 seconds or more have elapsed since the timer started instead of 50 or less (S107 N, S112 Y), it is determined that the detected electrode 361 is stagnant at the detection position or that the capacitance sensor IC 33 is abnormal. Then, the video controller 42 is notified (S115), and the process ends. If the CPU 40 determines that 2.0 seconds or more have not elapsed since the timer was started (S112, N), the CPU 40 continues the process of S107.

  In the sequence of the present embodiment, an example is given in which the time width is measured by the absolute value of the detection level. However, a sequence in which a stable initial level is detected, the rise and fall times are detected using the level + α as a threshold, the time width is measured, and then the table T is checked. In this manner, the CPU 40 can sequentially detect the remaining amount of toner by measuring the time width during which the capacitance sensor IC 33 is detecting the detected electrode 361 and collating it with the table T.

  According to the present embodiment, the following effects are obtained by the configuration and operation as described above. First, since the time interval during which the detected electrode 361 is detected increases from 100% to 0%, the remaining amount of toner can be detected sequentially until the toner is exhausted from the full state. In addition, since the capacitance sensor method has a high reaction speed, it can be performed simultaneously with an increase in detection time and an image forming operation. Further, since the warp of the detection mylar 351 is stable according to the remaining amount of toner even when rotating at a high speed, the remaining amount of toner can be detected sequentially.

  As described above, according to the present exemplary embodiment, the remaining amount of toner can be sequentially detected until the toner becomes empty from the full state, and the remaining amount of toner can be accurately detected even when the stirring member is operating at high speed. it can.

  In the first exemplary embodiment, the CPU 40 measures the remaining amount of toner in the time width during which the detected electrode 361 of the capacitance sensor IC 33 is detected. In this embodiment, the remaining amount of toner is measured from 30% to 100%, for example, 30% or more (predetermined amount or more) by the method of the first embodiment, and thereafter, for example, in the region of less than 30% (less than predetermined amount) The detection level (capacitance) of the capacitance sensor IC 33 is switched to detect the capacitance level. The CPU 40 (second measuring means) measures the remaining amount of toner based on the electrostatic capacity level. 1, 2, and 3 described in the first embodiment is also applied to the color laser printer of the present embodiment. The same components as those in the first embodiment are denoted by the same symbols, and detailed description thereof is omitted.

[Characteristics of toner remaining amount detection]
Next, the characteristics of the toner remaining amount detection in this embodiment will be described with reference to FIG. FIG. 6A is a characteristic graph of the remaining amount of toner (%) and the detection level of the capacitance sensor IC33. When the remaining amount of toner is large, the detection mylar 351 is greatly warped due to the resistance of the toner 28, and the detected electrode 361 passes far from the capacitance sensor electrode 321, so the detected electrode 361 and the capacitance sensor electrode 321. The capacitance between them becomes small. On the other hand, when the amount of toner 28 is small, the detected electrode 361 passes near the capacitance sensor electrode 321, so that the capacitance between the detected electrode 361 and the capacitance sensor electrode 321 increases.

  FIG. 6B is a table L showing the relationship between the detection level of the capacitance sensor IC 33 and the remaining amount of toner (%). Data of this table L is stored in the storage unit of the control board 80. Note that the sensitivity of the capacitance sensor IC33 of the table L is different from the sensitivity of the capacitance sensor IC33 of the table T in the first embodiment. For example, the detection level of the capacitance sensor IC33 corresponding to 10% of the remaining amount of toner in the table L is 190, but the detection level of the capacitance sensor IC33 corresponding to the remaining amount of toner of 10% in the table T is about 80. There are different values. The toner remaining amount between the table values is obtained by linear interpolation of the known toner remaining amount. Here, since the calculated detection level is a value in the present embodiment, the calculated detection level changes if the condition changes. The same applies to the numerical values of the table L for calculating the remaining amount of toner.

[Toner remaining amount detection flowchart]
Next, the flow of detection of the remaining amount of toner after the remaining amount of toner in this embodiment is less than 30% will be described with reference to the flowchart of FIG. Note that the period of the detection mylar 351 is also one rotation in about 1 second in the present embodiment as in the first embodiment. The processing in S201 and S202 in FIG. 7 is the same as the processing in S101 and S102 in FIG. When the CPU 40 determines that the detection level is 165 or less for 0.5 seconds or longer, the CPU 40 determines that the level is the initial state at the position where the detected electrode 361 is not present, and stores the average value therebetween as an initial value (S203 Y, S204). . If the CPU 40 determines that the detection level is 0.5 seconds or longer, not 165 or lower, but 2.0 seconds or longer (S203 N, S214 Y), the CPU 40 determines as follows. That is, the CPU 40 determines that any one of the capacitance sensor IC 33, the CPU 40, and the detection mylar 351 is abnormal, notifies the video controller 42 (S215), and ends. If the CPU 40 determines that 2.0 seconds or more have not elapsed since the start of reading the capacitance detection level (S214, N), the CPU 40 continues the process of S203.

Next, in order to detect that the detected electrode 361 has reached the detection position, the CPU 40 monitors whether the detection level is equal to or higher than [initial value] +10 (S205). When the CPU 40 determines that the detection level does not become [initial value] +10 or more and [initial value] ± 9 continues for 2.0 seconds or more (S213, Y), the detection mylar 351 or the electrode 361 to be detected is detected. The video controller 42 is notified (S215), and the process ends. When the CPU 40 determines that the detection level does not continue [initial value] ± 9 for 2.0 seconds or longer (S213, N), the CPU 40 continues the process of S205. When the CPU 40 determines that the detection level becomes [initial value] +10 or more during monitoring (S205, Y), the CPU 40 determines that the detected electrode 361 has reached the detection position, starts continuous reading, and performs reading. storing the value of the detection level (S206). If the CPU 40 determines that the detection level is [initial value] +10 or more for 8 msec (S207, Y), the CPU 40 determines that the detection level is normal and stores the maximum value (S208). If the CPU 40 determines that the detection level does not continue for [initial value] +10 or more for 8 msec, it continues the process of S205. When the CPU 40 determines that the maximum value data is not equal to 10 data (S209, N), the process returns to S205 (S209).

If the maximum value data is obtained for 10 data (S209, Y), the CPU 40 calculates an average value (toner remaining amount detection value) for 10 data of the maximum value (S210) and collates with the table L. (S211). The CPU 40 obtains the toner remaining amount between the table numerical values by linear interpolation of the known toner remaining amount. Thereafter, the CPU 40 informs the video controller 42 of the collated toner remaining amount (S212), and the process ends.

  According to the present embodiment, the following effects can be obtained by the above-described configuration and operation. First, since the capacitive sensor method has a high reaction speed, it can be performed at the same time as the detection time and the image forming operation. Further, since the warp of the stirring mylar 34 is stable in accordance with the remaining amount of toner even when rotating at a high speed, the remaining amount of toner can be detected. Furthermore, by combining the time width detection sequence at the timing when the capacitance changes in the first embodiment and the capacitance level detection sequence in the present embodiment, it is possible to deal with process cartridges of various configurations. Note that the remaining toner amount of 0% to 100% may be detected only by the capacitance level detection sequence.

  As described above, according to the present exemplary embodiment, the remaining amount of toner can be sequentially detected until the toner becomes empty from the full state, and the remaining amount of toner can be accurately detected even when the stirring member is operating at high speed. it can.

  In the first and second embodiments, the process cartridge 5 in which the detected electrode 361 includes one detection mylar 351 is taken as an example. In this embodiment, an example in which the detected electrode 361 is divided is given. For the color laser printer of this embodiment, the configurations and flowcharts of FIGS. 1 and 2 to 7 described in Embodiments 1 and 2 are applied. Further, the same configurations as those in the first and second embodiments are denoted by the same symbols, and detailed description thereof is omitted.

  FIG. 8 is a cross-sectional view of the developing unit and the capacitance sensor substrate 331 constituting the process cartridge 5 in this embodiment. FIG. 8A shows a state in which the remaining amount of toner is about 50%, and FIG. 8B shows a state in which the remaining amount of toner is about 10%. The detected electrode 361 is divided into two electrodes, a detected electrode 361a and a detected electrode 361b. The detected electrode 361a is disposed in the vicinity of the rotating shaft 25, and the detected electrode 361b is disposed in the vicinity of the tip of the detection mylar 351. . The length from the end of the detected electrode 361a on the rotating shaft 25 side to the end of the detected mylar 351 of the detected electrode 361b is the same as the length of the detected electrode 361 in the first and second embodiments, and is 30 mm. Yes (FIG. 8C). With such a configuration, the capacitance of the detected electrode 361a and the detected electrode 361b is detected, so the maximum value of the detection level is lowered, but the sensitivity of the capacitance sensor IC33 is ensured. Applicable when possible.

  According to the present embodiment, the following effects are obtained by the configuration and operation as described above. The area of the detected electrode 361 is reduced, and the cost is reduced accordingly. In addition, when the detection mylar 351 is prevented from warping by the waist of the detection electrode 361 when the detection electrode 361 is large as in the first and second embodiments, the detection electrodes 361a and 361b of this embodiment are used. Adequate warpage can be ensured by adopting. In the first embodiment and the third embodiment, an example in which the table T is referred to by one detection is shown for easy understanding. However, if the control is performed such that each table T is referred to after averaging the data a plurality of times, it can be expected that the detection accuracy is further improved.

  In the first to third embodiments, an example in which the developing unit is integrated is given. However, the present invention can also be applied to a replenishment type toner container in which a developing roller and a toner container are separated by providing a detected electrode and a detection mylar inside the toner container.

  As described above, according to the present exemplary embodiment, the remaining amount of toner can be sequentially detected until the toner becomes empty from the full state, and the remaining amount of toner can be accurately detected even when the stirring member is operating at high speed. it can.

28 Toner 40 CPU
321 Capacitance sensor electrode 351 Detect mylar 361 Detected electrode

Claims (6)

It rotates around the rotation axis in a detachable developing unit for accommodating a developer, a rotary member that having a flexible deflected by the resistance of the developer,
A first conductive member to be detected disposed on the rotating shaft side of the rotating member;
A second conductive member to be detected disposed on the tip side of the rotating member;
A detection electrode disposed on the outer wall near the developing unit,
A first capacitance between the first conductive member to be detected and the detection electrode; a second electrostatic capacitance between the second conductive member to be detected and the detection electrode; Converting means for detecting the combined capacitance and converting the capacitance into an electrical signal;
Measuring means for measuring a time width in which the electrical signal converted by the converting means exceeds a predetermined threshold; and
Determination means for determining the amount of the developer based on the time width measured by the measurement means;
An image forming apparatus comprising: It rotates around the rotation axis in a detachable developing unit for accommodating a developer, a rotary member that having a flexible deflected by the resistance of the developer,
A first conductive member to be detected disposed on the rotating shaft side of the rotating member;
A second conductive member to be detected disposed on the tip side of the rotating member;
A detection electrode disposed on the outer wall near the developing unit,
A first capacitance between the first conductive member to be detected and the detection electrode; a second electrostatic capacitance between the second conductive member to be detected and the detection electrode; Converting means for detecting the combined capacitance and converting the capacitance into an electrical signal;
Measuring means for measuring the detection level of the electrical signal converted by the converting means;
Determination means for determining the amount of the developer based on the detection level measured by the measurement means;
An image forming apparatus comprising: A rotating member installed on the rotating shaft that has the flexibility to rotate around the rotating shaft in a detachable developing unit that houses the developer and to be bent by the resistance of the developer;
A conductive member to be detected disposed on the rotating member;
A sensing electrode disposed near the outer wall surface of the bottom of the developing unit;
Conversion means for detecting the capacitance of the detected member and the detection electrode, and converting the capacitance into an electrical signal;
First measuring means for measuring a time width in which the electrical signal converted by the converting means exceeds a predetermined threshold;
Second measuring means for measuring a detection level of the electrical signal converted by the converting means;
Determining means for determining the amount of the developer based on the time width measured by the first measuring means or the detection level measured by the second measuring means;
When the determination unit determines that the amount of the developer is less than a predetermined amount based on the time width measured by the first measurement unit, the determination unit uses the second measurement unit. When the amount of the developer is determined based on the measured detection level, and when the amount of the developer is determined to be greater than or equal to the predetermined amount based on the time width measured by the first measuring unit Control means for controlling the judging means to judge the amount of the developer based on the time width measured by the first measuring means;
An image forming apparatus comprising: The image forming apparatus according to claim 3 , wherein the detected member is disposed in the vicinity of the rotation shaft of the rotating member and in the vicinity of the tip of the rotating member. The image forming apparatus according to claim 3 , wherein the detected member is one detected member that is disposed in the vicinity of the rotating shaft of the rotating member to the vicinity of the tip of the rotating member.   The image forming apparatus according to claim 1, further comprising a stirring member that rotates around the rotation shaft in the developing unit and stirs the developer.

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